The formation of catalyst pt nanodots by pulsed/sequential cvd or atomic layer deposition

Abstract

The disclosure describes a method of depositing a plurality Ft metal containing nanodots on a catalyst carbon support structure by forming a vapor of Pt(PF3)4, exposing a surface of the catalyst support to the vapor of Pt(PF3)4, purging the surface of the catalyst support with a purge gas to remove the vapor of Pt(PF3)4, exposing the surface of the catalyst support to a second reactant in gaseous form, purging the surface of the catalyst support with a purge gas to remove the second reactant, and repeating these steps to form a plurality of the Pt metal containing nanodots.

1 . A method of depositing Pt containing nanodots on a catalyst support structure, preferably a catalyst carbon support structure, the method comprising the steps of:
 a. forming a vapor of Pt(PF 3 ) 4 ,   b. exposing a surface of the catalyst support structure to the vapor of Pt(PF 3 ) 4 ,   c. purging the surface of the catalyst carbon support structure with a purge gas to remove the vapor of Pt(PF 3 ) 4 ,   d. exposing the surface of the catalyst carbon structure to a second reactant in gaseous form,   e. purging the surface of the catalyst carbon support structure with a purge gas to remove the second reactant,   f. repeating steps a. - e. to form a plurality of the Pt containing nanodots on the catalyst carbon support structure   wherein the temperature of the catalyst support structure during step a. and/or step b. is from 50° C. to 300° C.   
     
     
         2 . The method of  claim 1 , wherein the second reactant comprises an oxidizing agent selected from the group consisting of H 2 O, O 2 , O 3 , NO 2 , oxygen radicals and mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the second reactant comprises a reducing agent selected from the group consisting of H 2 , NH 3 , SiH 4 , Si 2 H 6 , Si 3 H 8 , SiH 2 Me 2 , SiH 2 Et 2 , N(SiH 3 ) 3 , hydrogen radicals, hydrazine, methylhydrazine, amines, NO, N 2 O, and mixtures thereof. 
     
     
         4 . The method of  claim 1 , wherein the second reactant is selected from the group consisting of H 2 , O 2 , and combinations thereof. 
     
     
         5 - 6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein the largest linear dimension of the nanodots has a range from 0.25 nm to 15 nm and/or a mean of 2 nm - 7 nm. 
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 1 , wherein each Pt containing nanodot comprises sufficient Pt so that a) the atomic percentage of Pt for the catalyst carbon support structure with the plurality of the Pt containing nanodots is from 0.5% to 3% and/or b) the weight percentage of Pt is from 5% to 50%. 
     
     
         10 . The method of  claim 1 , wherein the catalyst carbon support structure contains at least 30% Carbon by weight. 
     
     
         11 . The method of  claim 10 , wherein the plurality of Pt nanodots are formed directly on a carbon component of the catalyst carbon support structure. 
     
     
         12 . (canceled) 
     
     
         13 . The method of  claim 1 , further comprising a step of exposing the surface of the catalyst carbon support structure to a third reactant in gaseous form, wherein, if the second reactant is an oxidizing agent, the third reactant is a reducing agent, and vice versa. 
     
     
         14 . The method of  claim 13 , wherein the step of exposing the surface of the catalyst carbon support structure to the third reactant, is separated from step d. by step e. 
     
     
         15 . The method of  claim 14 , wherein the second reactant is oxygen and the third reactant is hydrogen. 
     
     
         16 . A method of depositing Pt containing nanodots on a catalyst support structure, preferably a catalyst carbon support structure, the method comprising the steps of:
 a. Forming a vapor of Pt(PF 3 ) 4 ,   b. Exposing a surface of the catalyst support structure to the vapor of Pt(PF 3 ) 4 , wherein step b. is for a time sufficient to form a plurality of the Pt containing nanodots on the catalyst support structure,   wherein the catalyst support structure is not exposed to any additional reactants to form the plurality of the Pt containing nanodots on the catalyst support structure, and   wherein the temperature of the catalyst support structure surface during step a. and/or step b. is from 50° C. to 300° C.   
     
     
         17 . The method of  claim 16 , wherein the largest linear dimension of the nanodots has a range from 0.25 nm to 15 nm and/or a mean of 2 nm - 7 nm. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 16 , wherein each nanodot comprises sufficient Pt so that a) the atomic percentage of Pt for the catalyst support structure with the plurality of the Pt containing nanodots is from 0.5% to 3% and/or b) the weight percentage of Pt is from 5% to 50%. 
     
     
         20 . The method of  claim 16 , wherein the catalyst support structure is a catalyst carbon support structure, preferably containing at least 30% Carbon by weight. 
     
     
         21 . The method of  claim 20 , wherein the plurality of Pt containing nanodots are formed directly on a carbon component of the catalyst carbon support structure. 
     
     
         22 . (canceled) 
     
     
         23 . A method of depositing Pt containing nanodots on a catalyst support structure, preferably a catalyst carbon support structure, the method comprising the steps of:
 a. forming a vapor of Pt(PF 3 ) 4 ,   b. exposing a surface of the catalyst support structure to the vapor of Pt(PF 3 ) 4  and an oxidizing agent, concurrently,   wherein step b. is for a time sufficient to form a plurality of the Pt containing nanodots on the catalyst support structure,   wherein the catalyst support structure is not exposed to any additional reactants to form the plurality of the Pt containing nanodots on the catalyst support structure, and   wherein the temperature of the catalyst support structure surface during step a. and/or step b. is from 50° C. to 300° C.   
     
     
         24 . The method of  claim 23 , wherein the oxidizing agent is selected from the group consisting of H 2 O, O 2 , O 3 , NO 2 , oxygen radicals and mixtures thereof. 
     
     
         25 . The method of  claim 24 , wherein the largest linear dimension of the nanodots has a range from 0.25 nm to 15 nm and/or a mean of 2 nm - 7 nm. 
     
     
         26 . (canceled) 
     
     
         27 . The method of  claim 23 , wherein each nanodot comprises sufficient Pt so that a) the atomic percentage of Pt for the catalyst support structure with the plurality of the Pt containing nanodots is from 0.5% to 3% and/or b) the weight percentage of Pt is from 5% to 50%. 
     
     
         28 . The method of any of  claim 23 , wherein the catalyst support structure is a catalyst carbon support structure, preferably containing at least 30% Carbon by weight. 
     
     
         29 . The method of  claim 28 , wherein the plurality of Pt containing nanodots are formed directly on a carbon component of the catalyst carbon support. 
     
     
         30 - 32 . (canceled)